Single fibers uniformly electrified were grounded to release the electric charge through the both ends of each sample. Decay of the electrification of the fibers, then, was observed by detecting photo-electrically the amplitude of fibers which were transversely vibrating in resonance with the alternating electrostatic force. On the assumption that these fibers can be regarded as cylindrical conductors, it is then possible to calculate expressions of the distribution of electric potential V(x, t) and the total charge Q(t) of the conductors in process of the decay of charge. where cs is the surface electric capacity per unit axial length, rs the surface electric resistance per unit length, V0 the initial electric potential and l the length of the conductors electrified. The expression Q(t) means that the logarithmic decay of the total charge is linear with time holding the inclination (π/l)2/csrs after a while since the decay has started. It, therefore, was checked with the solution displayed by the analog-computor and compared with the electrical detection of the amplitude of vibrating fibers. The time constant csrs estimated from this experimental method has clear physical meanings in contrast to the CR which is conventionally used as the lumped constant of fibers and fiber assemblies.
This paper describes the model analysis to calculate the effective thermal conductivity parallel to fiber axes of unidirectionally oriented fiber assembly. This analysis takes account of not only the heat conduction but also the heat radiation as the same way in the previous paper. The property of this heat transfer is discussed and compared with the result perpendicular to fiber axes obtained in previous paper2). The conclusions are as follows. (1) From this analysis, the conductive and the radiative (between the two plates) components of the effective thermal conductivity parallel to fiber axes tend to the same behavior as that perpendicular to fiber axes obtained in the previous paper. However, the radiative component between fiber and plate is different from that perpendicular to fiber axes and holds approximately constant regardless of the change of the volumetric ratio. (2) The effective thermal conductivity consisting of those three components has the minimum value when the volumetric ratio is about 0.005 less than that perpendicular to fiber axes. Furthermore, the value of the effective thermal conductivity parallel to fiber axes is larger than that perpendicular to fiber axes, and this difference is due to the difference of the radiative heat transfer between fiber and plate.
The ζ-potentials and dyeing properties of formalized poly(vinyl alcohol) (PVA) fiber (I) and its acid-treated product (II) in aqueous solutions of a direct dye, Benzopurpurine 4B, have been studied. The ζ-potentials of the fibers were measured by the streaming-potential method. The surface dye adsorption (Ms) of the fibers was calculated from the ζ-potentials obtained and the total dye adsorption (Mt) was determined by the colorimetric method. The negative ζ-potentials and Ms for I and II increased with an increase in the degree of formalization of the fibers. On the other hand, Mt, the surface area (Sa) covered by dye molecules, and the degree of swelling of these fibers decreased with increasing degree of formalization. The negative ζ-potentials and Ms for I were fairly larger than those for II. However, Mt, Sa, and the degree of swelling for the former were considerably smaller than those for the latter. It is apparent that the surface dyeing behavior of I and II with the direct dye is remarkably different from the total dyeing behavior of these fibers.
In scanning the surface of fabrics with a light spot, we can get the power of the reflection or transparency that periodically changes according to disposition, diameter or bend of the threads. Then, on application of a digital computer, a digital pattern of fabric is represented by a twodimentional array of points showing the reflection and transparency distributions of fabrics by a suitable scanning light spot. On detecting the defects by the reflection or transparency from fabrics, it is necessary to design the size and shape of the scanning light spot at the fabrics in consideration of the some kinds of defects and the inherent noises being due to the normal fabric structures, also the frequency band determined by the resolving power and the scanning speed that are suitable to the electric amplifier system. In general, the spaces between the threads in fabrics are much smaller than the thread diameters. When width of the scanning light spot is smaller than the thread diameter, we can detect the characters of the thread and thread interval in every each warp direction. When length of the scanning light spot is a little larger than the thread diameter, average characters of a few threads will be detected, eliminating the noises caused by the twists and fluffes of the threads. In our experiments, the width of the scanning light spot was set 0.2mm and length 5mm in consideration of practrical usefulness. Moreover, the frequency band f needed to design of the electro-optical amplifier is given by f=V/2b where V is scanning speed of the light spot, 240×103mm/sec, and b is resolving power, 0.2mm. Confirmation of the size and shape of the light spot, transient properties and frequency responses of the signal transduser was discussed with the some experimental equipments.